Miscibility Data Research Articles

High-entropy alloy screening for halide perovskites.

As the concept of high-entropy alloying (HEA) extends beyond metals, new materials screening methods are needed. Halide perovskites (HP) are a prime case study because greater stability is needed for photovoltaics applications, and there are 322 experimentally observed HP end-members, which leads to more than 1057 potential alloys. We screen HEAHP by first calculating the configurational entropy of 106 equimolar alloys with experimentally observed end-members. To estimate enthalpy at low computational cost, we turn to the delta-lattice parameter approach, a well-known method for predicting III-V alloy miscibility. To generalize the approach for non-cubic crystals, we introduce the parameter of unit cell volume coefficient of variation (UCV), which does a good job of predicting the experimental HP miscibility data. We use plots of entropy stabilization versus UCV to screen promising alloys and identify 102 HEAHP of interest.

In Situ Compatibilized Blends of PLA/PCL/CAB Melt-Blown Films with High Elongation: Investigation of Miscibility, Morphology, Crystallinity and Modelling.

Ternary-blended, melt-blown films of polylactide (PLA), polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were prepared from preliminary miscibility data using a rapid screening method and optical ternary phase diagram (presented as clear, translucent, and opaque regions) as a guide for the composition selection. The compositions that provided optically clear regions were selected for melt blending. The ternary (PLA/PCL/CAB) blends were first melt-extruded and then melt-blown to form films and characterized for their tensile properties, tensile fractured-surface morphology, miscibility, crystallinity, molecular weight and chemical structure. The results showed that the tensile elongation at the break (%elongation) of the ternary-blended, melt-blown films (85/5/10, 75/10/15, 60/15/25 of PLA/PCL/CAB) was substantially higher (>350%) than pure PLA (ca. 20%). The range of compositions in which a significant increase in %elongation was observed at 55−85% w/w PLA, 5−20% w/w PCL and 10−25% w/w CAB. Films with high %elongation all showed good interfacial interactions between the dispersed phase (PCL and CAB) and matrix (PLA) in FE-SEM and showed improvements in miscibility (higher intermolecular interaction and mixing) and a decrease in the glass transition temperature, when compared to the low %elongation films. The decrease in Mw and Mn and the formation of the new NMR peaks (1H NMR at 3.68−3.73 ppm and 13C NMR at 58.54 ppm) were observed in only the high %elongation films. These are expected to be in situ compatibilizers that are generated during the melt processing, mostly by chain scission. In addition, mathematical modelling was used to study the optimal ratio and cost-effectiveness of blends with optimised mechanical properties. These ternary-blended, melt-blown films have the potential for use in both packaging and medical devices with excellent mechanical performance as well as inherent economic and environmental capabilities.

Martini 3: a general purpose force field for coarse-grained molecular dynamics.

The coarse-grained Martini force field is widely used in biomolecular simulations. Here we present the refined model, Martini 3 ( http://cgmartini.nl ), with an improved interaction balance, new bead types and expanded ability to include specific interactions representing, for example, hydrogen bonding and electronic polarizability. The updated model allows more accurate predictions of molecular packing and interactions in general, which is exemplified with a vast and diverse set of applications, ranging from oil/water partitioning and miscibility data to complex molecular systems, involving protein-protein and protein-lipid interactions and material science applications as ionic liquids and aedamers.

Impact of Drug-Polymer Miscibility on Enthalpy Relaxation of Irbesartan Amorphous Solid Dispersions.

Drug-polymer miscibility has been proposed to play a critical role in physical stability of amorphous solid dispersions (ASDs). The purpose of the current work was to investigate the role of drug-polymer miscibility on molecular mobility, measured as enthalpy relaxation (ER) of amorphous irbesartan (IBS) in ASDs. Two polymers, i.e. polyvinylpyrrolidone K30 (PVP K30) and hydroxypropyl methylcellulose acetate succinate (HPMCAS), were used to generate ASDs with 10% w/w of the polymer. Drug-polymer miscibility was determined using melting point depression (MPD) method. Molecular mobility was assessed from ER studies at a common degree of undercooling (DOU) (Tg - 13.0°C ± 0.5°C). IBS exhibited higher miscibility in PVP K30 as compared to HPMCAS at temperature > 140°C. However, extrapolation of miscibility data to storage temperature (62°C) using Flory-Huggins (F-H) theory revealed a reversal of the trend. Miscibility of IBS was found to be higher in HPMCAS (2.6%) than PVP K30 (1.3%) at 62°C. Stretched relaxation time (τβ) of 17.4365h and 7.0886h was obtained for IBS-HPMCAS and IBS-PVP K30 ASDs, respectively. Miscibility of drug-polymer at storage temperature explained the behavior of the molecular mobility, while miscibility near the melting point provided a reverse trend. Results suggest that drug-polymer miscibility determined at temperatures higher than the storage temperature should be viewed cautiously.

Miscibility performance of trans-1,3,3,3-tetrafluoroprop-1-ene and its binary blends with lubricating oil

In order to investigate the performance of R1234ze(E) and its blends with lubricating oil in refrigeration system, the miscibility should be well understood firstly. The critical miscibility temperature (TCMT) data of different mass fraction of R1234ze(E) and its blends (R600a, R32) with lubricating oils (a 3GS naphthenic mineral oil and polyol ester (POE) oil) were measured and analyzed at temperature ranging from 220.15 to 310.15 K in this paper. The miscibility data were correlated with a Modified Element Contribution Evaluation Method and an evaluation equation, which was proposed to predict the miscibility of the binary blends. It was concluded that R600a promoted the miscibility of R1234ze(E)/R600a with mineral oil while R1234ze(E) blocked it. For the mixed solution of R1234ze(E)/R32 with POE oil, the more R32 had the better miscibility shown, while the more R1234ze(E) was the worse miscibility performed.

Extensive Accuracy Test of the Force-Field-Based Quasichemical Method PAC–MAC

We present a comprehensive evaluation of the recently developed pair configuration to molecular activity coefficient (PAC–MAC) method. PAC–MAC is a force-field-based quasichemical method for rapid calculation of binary phase diagrams. The accuracy of the method is tested by comparing the calculated excess mixing free energy with experimental data for 1092 binary mixtures. The root mean squared error (RMSE) is shown to be 0.15 kBT. Furthermore, a comparison with UNIFAC and molecular simulations is performed. UNIFAC shows a significantly higher accuracy (RMSE: 0.07 kBT), whereas molecular simulations lead to comparable results. The accuracy of both molecular simulations as well as PAC–MAC depends highly on the used force field. The binary parameters of UNIFAC are optimized using experimental miscibility data, whereas the force field parameters are not. Therefore, a better performance of UNIFAC is expected. A concise data set shows the capacity of PAC–MAC in predicting results obtained using Monte Carlo simu...

SOLUBILITY AND MISCIBILITY OF REFRIGERANTS R407C AND R410A WITH SYNTHETIC COMPRESSOR OILS

In this paper, solubility and low temperature miscibility of refrigerants R407C and R410A in four different commercial Polyolester (POE) lubricants, produced by the same company but with different ISO standard viscosity grade, are measured with the aim to evaluate the possible correlation of solubility and miscibility with standard viscosity of the lubricant. Vapor pressure (solubility) is measured using calibrated, constant volume cells at oil mass fractions 30, 50, 70, 80, and 90% over a temperature range from -20 to 100 °C, and pressures up to 5 MPa. The measurements of low temperature miscibility limit (lower critical solution temperature LCST) were made using high-pressure sapphire cell. LCST was directly obtained by visual observation of a «milky haze» followed by a phase separation. Miscibility data were obtained at oil mass fractions from 5 to 50% over a temperature range from -60 to 0 °C. A set of simple equations was derived to describe the experimental results. Analysis of the obtained results showed that the solubility of refrigerant/lubricant mixtures depends weakly on the viscosity grade of the oil. At the same time, the miscibility gap (LCST) differ much bigger for various refrigerant/lubricant mixtures. The lower viscosity grade of the oil, the lower LCST of the refrigerant/lubricant mixture. LCSTs for the mixtures of R407C with the lubricants with the viscosity grades 32 and 220 differ by 30-45 °С.

Studies on the miscibility and effect of the addition of urea to poly(acrylic acid) and poly(sodium styrene sulfonate) blends by dilute solution viscometry method

The miscibility of poly(acrylic acid) (PAA) and poly(sodium styrene sulfonate) (PSSNa), in H2O was investigated by a dilute solution viscometry method (DSV). The miscibility of the polymer blend was investigated on the basis of the signs of the interaction parameters Δ[b]m, Δ[η]m, ΔB and μ. The results from the viscosity method were correlated with the miscibility data obtained for the same blend by Fourier transform infrared and differential scanning calorimetry. These investigation indicated that the examined blend was miscible for all composition ratios examined (w2 = 0.10, 0.25, 0.50, 0.75, and 0.90).The addition of urea to the polymer mixture H2O (1)/PAA (2)/PSSNa (3) decreased the miscibility.

Influence of Miscibility of Protein-Sugar Lyophilizates on Their Storage Stability.

For sugars to act as successful stabilizers of proteins during lyophilization and subsequent storage, they need to have several characteristics. One of them is that they need to be able to form interactions with the protein and for that miscibility is essential. To evaluate the influence of protein-sugar miscibility on protein storage stability, model protein IgG was lyophilized in the presence of various sugars of different molecular weight. By comparing solid-state nuclear magnetic resonance spectroscopy relaxation times of both protein and sugar on two different timescales, i.e., (1)H T1 and (1)H T1ρ, miscibility of the two components was established on a 2-5- and a 20-50-nm length scale, respectively, and related to protein storage stability. Smaller sugars showed better miscibility with IgG, and the tendency of IgG to aggregate during storage was lower for smaller sugars. The largest sugar performed worst and was phase separated on both length scales. Additionally, shorter protein (1)H T1 relaxation times correlated with higher aggregation rates during storage. The enzyme-linked immunosorbent assay (ELISA) assay showed overlapping effects of aggregation and chemical degradation and did not correspond as well with the miscibility. Because of the small scale at which miscibility was determined (2-5nm) and the size of the protein domains (∼2.5 × 2.5 × 5nm), the miscibility data give an indirect measure of interaction between protein and sugar. This reduced interaction could be the result of steric hindrance, providing a possible explanation as to why smaller sugars show better miscibility and storage stability with the protein.

Plait point in ternary system with a miscibility gap: Analysis of the procedures involved in its determination and development of novel procedures

Ternary miscibility data, usually reported in the Roozeboom triangular diagram, have been analyzed in Cartesian coordinates defined by X=(xi−xj)/3 and Y=xk where xi, xj, and xk are the mole fractions of the two solvents and of the solute, respectively. This has allowed for an easy analytical representation of all the elements which are characteristic of the system: binodal curve, tie lines, plait point. Three novel methods for determining the plait point composition have been proposed based only on its fundamental properties. The results have been presented by applying the methods to some systems described in the literature. Differences between the values obtained with the proposed methods and those obtainable with the NRTL and UNIQUAC models have been found and are discussed.

Miscibility Measurement and Evaluation for the Binary Refrigerant Mixture Isobutane (R600a) + 1,1,1,2,3,3,3-Heptafluoropropane (R227ea) with a Mineral Oil

The miscibility of refrigerants with mineral oils is very important in the process of refrigerant substitution. The experimental critical solubility temperature (TCST) for the binary refrigerant mixture isobutane (R600a) + 1,1,1,2,3,3,3-heptafluoropropane (R227ea) in varying proportions with a 3GS (viscosity, ISO 32) naphthenic mineral oil was determined over a wide temperature range from 223.15 K to 303.15 K, and over an oil mass fraction range from 5 % to 20 %. A method based on analysis of the element type and number was proposed not only for evaluating the miscibility degree of pure refrigerants, but also for fitting miscibility data of the binary refrigerant mixture R600a/R227ea with the mineral oil. The miscibility evaluation result of R600a/R227ea with the mineral oil was calculated and shown on a triangular diagram which included five regions, standing for the area of TCST over 303.15 K, between 273.15 K and 303.15 K, between 253.15 K and 273.15 K, between 233.15 K and 253.15 K, and below 233.15 K, respectively. The diagram showed that when the mass fraction of R600a was below 20 % in the R600a/R227ea/mineral oil solution, a second liquid phase (oil-rich phase) would appear under common air-conditioning refrigeration temperatures; when the mass fraction of R600a was over 30 %, the liquid phase would not appear.

Miscibility of ternary systems containing kerosene-based surrogate fuel and hydrous ethanol: Experimental data + thermodynamic modeling

Limited miscibility may be a major concern for the use of ethanol in jet fuels particularly when water is present. Herein miscibility data were obtained for mixtures composed of a kerosene-based surrogate fuel (80% n-decane and 20% 1,2,4-trimethylbenzene by mass), ethanol and water in varying percentages at −1.7°C, 11.4°C, 25°C and 66°C. The results indicated that the purity requirement of hydrous ethanol increased with the surrogate fuel percentage. The purity requirement increased when the temperature decreased. The upper limit for water tolerance was largely above the azeotropic value (4.4% water content) at 25°C and 66°C, which indicated that the blends can be miscible at room temperature and above even though water content is higher than the azeotrope concentration. In addition, emulsifier, in the low percent range (below 2% by volume), was shown to have notable effects on the phase behavior of the ternary mixtures. Liquid–liquid equilibrium (LLE) experimental data at 101.32kPa were compared with simulation results by means of the UNIFAC-LLE model, which provided satisfactory results with moderate deviation from experimental data. A Matlab-based program was developed to determine the compositions of individual phases for any initial mixtures with known compositions.

Investigating the miscibility of polystyrene/poly(styrene-co-acrylonitrile) blend in tetrahydrofuran by simple physical techniques at various temperatures

The miscibility of polystyrene and poly(styrene-co-acrylonitrile) blend in tetrahydrofuran was investigated by viscometric, density, and refractometric methods over an extended range of concentration, composition, and temperature. The miscibility of the polymer blend was investigated on the basis of the sign of the interaction parameters α, β, μ, ΔB, and Δ[η]m. The results from the viscosity method were correlated with the miscibility data obtained for the same blend by refractive index and density methods. These investigations indicated that the examined blend was immiscible over the investigated composition and temperature range.

Viscometric Analysis of Miscibility and Interactions for Binary, Ternary Polycarbonate/Brominated Polystyrene + Chloroform Systems at Different Temperatures

Viscosities of ternary systems consist of polycarbonate (PC)/brominated polystyrene (PBrS) in chloroform and their corresponding binary systems were measured at different temperatures (20, 25, and 30°C). All the measurements were carried out at the concentration ranges of 0.1–0.6 g·dL−1. The mass ratio of PC to PBrS was selected as 75:25, 50:50, and 25:75 in the ternary solutions. Two empirical expressions of Huggins and Kraemer equations with three-parameters were used for reproducing of the experimental viscosity data. The fitting parameters were obtained for the corresponding temperatures. The miscibility criteria on the basis of the sign of Δ[η]m based on the difference between experimental and ideal values of [η]m, was calculated by applying the Garcia et al., theoretical equation. The effect of temperature on the viscosity data was also studied. The results from this method were correlated with the miscibility data obtained for the same system by differential scanning calorimeter (DSC) findings.

Solubility of Carbon Dioxide in Pentaerythritol Tetrabutyrate (PEC4) and Comparison with Other Linear Chained Pentaerythritol Tetraalkyl Esters

Carbon dioxide (CO2) is one of the most promising natural refrigerants that can be employed as an alternative to hydrofluorocarbons (HFC), due to its low global warming potential (GWP). Nevertheless, CO2 presents several technical problems when employed as a working fluid in refrigeration systems. In particular, the selection of the most suitable lubricant for each application is far from being resolved. The thermodynamic behavior of a CO2+lubricant system must be well-known for a correct oil selection. This work is part of a research project to study the solubility of CO2 in commercial oils and their precursors. Here, solubility measurements of CO2 in pure pentaerythritol tetrabutyrate (PEC4) between 243 K and 343 K are presented and compared with miscibility data of CO2 in pentaerythritol tetrahexanoate (PEC6) and pentaerythritol tetraoctanoate (PEC8). The experimental data were correlated with a thermodynamic model based on a cubic equation of state with Huron–Vidal mixing rules and the UNIQUAC equation for the excess Gibbs energy at infinite pressure.

Phase diagram for the hexane-[Y(NO3)3(TBP)3]-acetonitrile liquid ternary

A phase diagram for the hexane-[Y(NO3)3(TBP)3]-acetonitrile (1-2-3) liquid ternary at T = 298.15 K was studied. This ternary consists of two pairs of incompletely miscible liquids (hexane-acetonitrile and [Y(NO3)3(TBP)3]-hexane). It contains two homogeneous liquid fields and one two-phase liquid field. One phase is depleted of acetonitrile and contains variable proportions of [Y(NO3)3(TBP)3] and hexane; the other contains variable proportions of acetonitrile and [Y(NO3)3(TBP)3] and small proportions of hexane. Intermolecular interaction parameters and excess Gibbs energies g E were calculated for binaries and the liquid ternary along binodal curves proceeding from miscibility data for the [Y(NO3)3(TBP)3]-hexane and hexane-acetonitrile binaries and the liquid ternary and using equations of the NTRL model. For the liquid ternary, g E > 0.g E decreases in the following order of pairs of liquids: (1, 3), (1, 2), (2, 3). A computer algorithm is given for calculating binodal curves and tie-lines for the liquid ternary with the use of equations of the NTRL model proceeding from the intermolecular interaction parameters.

Binary Vapor–Liquid and Vapor–Liquid–Liquid Equilibria of Hydrofluorocarbons (HFC-125 and HFC-143a) and Hydrofluoroethers (HFE-125 and HFE-143a) with Ionic Liquid [emim][Tf2N

Solubility behaviors of binary HFC-125 (CF3−CF2H), HFE-125 (CF3−O−CF2H), HFC-143a (CF3−CH3), and HFE-143a (CF3−O−CH3) systems with room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) have been studied using a gravimetric microbalance method from (283 to 348) K and/or volumetric and cloud-point methods. Vapor–liquid equilibrium (VLE) data for HFC-125 + [emim][Tf2N] and HFE-125 + [emim][Tf2N] systems have been well correlated with our equation-of-state (EOS) model, which predicted vapor–liquid–liquid equilibria (VLLE) for both of these binary systems, and the VLLE have been experimentally proved. As for the binary systems of HFC-143a + [emim][Tf2N] and HFE-143a + [emim][Tf2N], only VLLE experiments have been made, and partial miscibility (temperature and composition: VLLE−Tx) data are well correlated with the NRTL (nonrandom two-liquids) activity model. While the immiscibility gap of the HFC-125 binary system is smaller than that of the HFE-125 system, ...

Viscometric study on the miscibility of polystyrene/brominated polystyrene blends

The miscibility of polystyrene/brominated polystyrene blends (PS/PBrS) was investigated by using dilute-solution viscometry (DSV) method. The intrinsic viscosity and the viscometric parameters of this system have been determined at 20 ± 0.1 °C for prepared several PS/PBrS compositions (85/15, 75/25, 50/50, 25/75, 10/90). The binary systems were prepared in chloroform at five different concentrations; 0.15, 0.30, 0.60, 0.90, 1.20 g 100 ml −1. The miscibility criteria on the basis of the sign of Δ[ η] m , Δ b and Δ b′, which are based on the difference between experimental and ideal values of [ η] m , and b m were calculated by applying the Garcia et al., Catsiff–Hewett and Krigbaum–Wall theoretical equations. The thermodynamic parameter, α, modified thermodynamic parameter, β, and interaction parameter, μ, were also estimated. The data obtained from the viscometry studies showed that the examined blends were immiscible in all the compositions range besides the composition (10/90). The results from the DSV method are correlated with the miscibility data obtained for the same blend by differential scanning calorimetry (DSC) find.

Effect of monomer sequence on miscibility in statistical copolymer blends and estimation of segmental χ parameters from their miscibility

AbstractMiscibility in statistical AB/AB copolymers was investigated from the viewpoint of the copolymer sequence effect based on the Balazs theory. The AB copolymers used were poly[(p‐chlorostyrene)‐co‐(hexyl methacrylate)], poly(styrene‐co‐HMA) and poly[(methyl methacrylate)‐co‐HMA]. Miscibility in the former two systems displayed deviation from the Flory–Huggins theory extended to statistical copolymers, and such behavior was interpreted as the sequence effect based on the Balazs theory. From calculations of the probabilities, Z, of interactions between triads, changes in Z for AAA/BBB, AAA/BBA, AAA/ABA, AAB/BBB and BAB/BBB were remarkable around the miscibility boundaries. In order to obtain insight into the miscibility behavior, we related the interaction parameters for the triads, i.e. χAAA/BBA = χAAA/ABA, χAAB/BBB = χBAB/BBB, and χAAB/BBA = χBAB/BBA = χAAB/ABA = χBAB/ABA. Using the above treatment, the χ parameters were estimated from the experimental miscibility data. Reproducibility in miscibility was good for all of the systems. In addition, the parameters were comparable to those obtained by using the Cantow–Schulz assumption. Copyright © 2004 Society of Chemical Industry

Interpretation of unusual textures in the B2 phase of a liquid crystal composed of bent-core molecules.

A liquid crystal material of bent-core molecules is investigated by means of optical texture observations, x-ray measurements, and miscibility studies. While the x-ray and miscibility data point towards a B2 phase, the texture is however unusual, showing optical isotropy and segregation in two domains with opposite gyrations. It is shown that the texture can be interpreted successfully in terms of a smectic-C(A)P(A) structure in small domains with random orientations. The optical activity data are also explained semiquantitatively.